1. Field of the Invention
The present invention relates to an inspection method of a secondary battery, and relates to, for example, an inspection method of a secondary battery, the inspection method including a low-temperature output inspection to guarantee a low-temperature output.
2. Description of Related Art
In an inspection step of a secondary battery, there is a low-temperature output inspection to guarantee an output capability in a case where the secondary battery is put under a low-temperature environment. Japanese Patent Application Publication No. 2013-084508 (JP 2013-084508 A) includes a step of setting a state of charge (SOC) of a secondary battery to 3% to 15%, and a step of measuring a resistance of the secondary battery having a SOC of 3% to 15%, under an environment of 10° C. to 30° C. Further, in the technique described in JP 2013-084508 A, a measurement step is performed after an aging step, and a low-temperature output inspection is performed based on a result of the measurement in the measurement step.
However, in a case where the low-temperature output inspection is performed after the aging step, the low-temperature output inspection is performed based on a voltage drop amount after a formation reaction of a SEI coating is completed. Therefore, a measured resistance (e.g., a reaction resistance) of the secondary battery is small, which causes a problem that measurement accuracy cannot be secured sufficiently. Further, in a case where aging is performed after the inspection step, battery performance changes due to aging, which may decrease a correlation between the measured voltage drop amount and a low-temperature output.